The present invention relates to continuous transverse stub antenna arrays, and more particularly, to the use of phase tuning sections in a continuous transverse stub antenna array that permit phase tuning of each element so that the elements may be spaced periodically.
Continuous transverse stub antenna arrays are described in U.S. Pat. No. 5,266,961 issued Nov. 30, 1993, entitled "Continuous Transverse Stub Element Devices and Method of Making Same ", U.S. patent application Ser. No. 08/104,020 filed Aug. 10, 1993, entitled "Continuous Transverse Stub Element Antenna Arrays", both of which are assigned to the assignee of the present invention. The elements of the continuous transverse stub antenna array must be tuned in order to optimize the performance of the array.
The current method of tuning each element is to vary the spacing between adjacent antenna elements. Once the elements are shifted to account for tuning, the amplitude and phase of the array requires adjustment. By a process of iteration, the interpolated amplitude and phase of each element is obtained. The result is an array that is aperiodic in spacing and approximate in amplitude and phase at each element.
The disadvantages of aperiodic arrays are that their antenna patterns have wider beamwidths, higher side-lobe levels, and consequently, lower gain than equivalent periodically spaced arrays. The present invention eliminates the need to vary the spacing between antenna elements in a continuous transverse stub antenna array.
Therefore, it is an objective of the present invention to provide for a continuous transverse stub antenna array that uses phase tuning sections to phase tune each element so that the elements may be spaced periodically.